Polymer transport across isotope-selective interdiffusion barriers

¹ Material Science and Engineering Laboratory, National Institute of Standards and Technology (NIST) - Gaithersburg, MD 20899-8542, USA
² Philips Research Laboratories - 5656 AA Eindhoven, The Netherlands
³ Virginia Polytechnic Institute and State University, Department of Chemistry Blacksburg, VA 24061, USA

Corresponding authors: holger.gruell@philips.com aesker@vt.edu

Received: 26 February 2001
Accepted: 19 November 2001

Abstract

Neutron reflectivity experiments were performed to study the interdiffusion of two compatible polymers, polystyrene and deuterated polystyrene, across a free-standing ultra-thin (60 Å) interstitial membrane. Annealing above the glass transition temperature and quenching back to room temperature allows for a time-dependent study of the changing concentration profile due to membrane-mediated interdiffusion. For the case of matched polymer molecular masses but different isotopic labeling, faster transport of the deuterated polymer across the interstitial layer is observed leading to displacement of the membrane. Varying the molecular mass and isotopic labeling of the top polymer layer provides information about the size discrimination and isotopic selectivity of the membrane.